Party-line telephone.



c'. A. sows & A. H. GRAVES.

PARTY LINE I.ELEPHOI\TE. APPLICATION FILED HA3. 4, 1901.

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C. A. SOANS & A. GRAVES.

' PARTY LINE TELEPHONE.

APPLICATION-FILED MAR. 4, 1901.

97 ,95 1 Patented Dec. 20, 1 910.

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APPLICATION FILED MAR.4, 1907.

Patented Dec.f20, 1910.

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'nuirnp STATES PATENT FFIGE,

CYRIL A. SOANS AND ALBERT. H. GRAVES, OF CHICAGO, ILLINOIS, ASSIGNORS,MESNE ASSIGNMENTS, TO HOMER ROBERTS TELEPHONE 00., A CORPORATION OF WESTVIRGINIA.

PARTY-LINE TELEPHONE.

Specification of Letters Patent.

Patented Dec. 20, 1.910.

Application filed March 4, 1907. Serial No. 360,352.

residing at Chicago, in the county of Cook.

and State'of Illinois, and ALBERT H. GRAVES, a citizen of the UnitedStates, residing at said Chicago, Illinois, have invented certain newand useful Improvements in Party- Line Telephones, of which thefollowing is a specification.

This invention relates to improvements in party-line telephones, andrefers more specifically to systems of that character commonlydesignated as lock-out systems;

Among the salient objects of the invention are to so organize andconstruct the substation apparatus and circuits that the main orselecting relay of each sub-station may be located at the junctureof-the drop wires with the main line wires and the telephone set properarranged at the ends of the drop wires or at any desired distance fromsaid relay, thereby avoiding the necessity of looping inmore than asingle pair of drop wires; to so organize a system of that character inwhich one of the line wires is in sections which are built up or unitedfrom station to station, that the buildingup of the line (in so far asmechanical operation is concerned) depends only upon the properoperation of a single relay at each sub-station, thereby minimizing theinterdependency of the several stations; to provide in a system of thegeneral character last mentioned, in conjunction with each instrumentwhich normally operates to build up the sectional line an emergencyrelay whose function is to act as a substitute for the main relay incase the latter becomes inoperative; to provide in a party-linetelephone system a line construction which while normally sectional asregards direct current is nevertheless continuous as regardsalternating, 2'. 6., talking current; to provide in conjunction with aline construction characterized as last mentioned, improved, means forplacing a plurality of subscribers I upon the same line in talkingconnection with each other; to provide improved means whereby anvsubscribers telephone set which has been given talking connection may berestored locally, 2'. 6., without restoring the entire line, therebyenabling the exchange operator to answer calls progressively over theentire length of the line as distinguished from commencing at theinitial end after disposing of each talking connection; to provide asystem so organized that the simple act by a subscriber of removing thereceiver from the switch-hook both sends in a call for connection andsets the station for automatic selection by the exchange operator, butnevertheless in case the subscriber abandons the call and returns thereceiver to the switch-hook, the set condition of his station iseliminated; to provide in a system organizedin general as lastmentioned, means whereby upon the automatic location and selection of acalling sub-station, and without further move on the partof the exchangeoperator; to provide in..a system of the general character describedimproved means for automatically arresting the building up of thesectional line and thereby locating a calling station; .to provide animproved polarized relay or magnet and associated switch contactswhereby said contacts may be latched or locked in one position bysending current through the magnet of one polarity, and the samecontacts released or restored by sending current of opposite polaritythrough the magnet; to provide in a partyline svstem of the generalcharacter described a system of calling in signals and a system ofclearing out or supervisory signals, both signal systems being to allpractical intents entirely independent of each other and non-interferinand in general to provide simplified and improved mechanism, circuitsand cooperative arrangements in systems of the general characterreferred to.

To the above ends the invention consists in the matters hereinafterdescribed and more particularly pointed out in the appended claims.

The invention will be readily understood from the following description,reference being had to the accompanying drawings forming apart thereofand in which Figures 1 and 2 taken together show diagrammatically apreferred embodiment of the system; Fig. 3 is a front elevation of one 5upper end of the biasing bar being broken away in each instance; Fig. 7is a fragmentary detail, partly in section, of the contact group of theselecting relay; Fig. 8 is a similar detail of the contact group of theringer; Fig. 9 is a sectional detail through the armature ofthe ringershowing the connection of the clapper therewith.

Referring to the drawings, Fig. 1 shows the central station equipment,and Fig. 2 the sub-station equipment and line wires.

A, B and C, respectively, designate keys interposed in the cord circuitat the exchange, D designates as a whole a controlling relay, E anautomatic impulse counter or selector, F a pole changer, (Jr a linedrop, and H a supervisory signal set. In the external part of the systemI and 1, respectively, designate the telephone sets proper, J and J,respectively, corresponding main selecting relays, which for convenienceof description will be hereinafter designated pole relays, K a groundinginstrument at the end of the line (hereinafter termed the grounder), andM an emergency relay which is operatively associated with one of thepole relays.

Describing first the external circuits and sub-station apparatus, L andR designate the main lines, and L and R the drop wires. At the junctureof each pair of drop wires with the main lines is located a pole relay,as J, this instrument being constructed in general similarly to anordinary polarized magnet, comprising the usual pair of spools, heelpiece, armature and biasing bar, all as hereinafter more specificallydescribed. The windings of this instrument are, however, peculiar inthat they are so arranged that the windings of one spool are included inboth the right and left main lines, while the winding of the other spoolis electrically connected with one of the drop wires.

Tracing the circuits through this instrument, line wire L extends to andincludes one winding; of spool 1, thence extends beyond unbrokenly tothe next sub-station. The right main line also extends to and includesone winding of the spool 1, being wound upon the latter in the samedirection as is tl e left hand line, extends thence to and is connectedwith the switch-spring 2 of a group of contact springs controlled by thearmature 3 of the relay. Normally the switclrspring rests in contactwith an upper spring 1, and from the latter a conductor 5 leads to andincludes the winding of the spool 1 and thence extends to the telephoneset proper as the right drop wire R. A condenser 6 is interposed in aconductor as a shunt across the winding of the spool 1.. The right mainline is normally in sections extending from station to station, and thelower spring 7 of the group referred to is connected with the initialend of the suc- 7 ceeding section of said right main wire. A

shunt conductor 8 connects the switchspring 2 with the contact spring 7,and a condenser 9 is interposed in this shunt. Switclrspring 2 isdepressed into engagement with lower spring 7 by the downward movementof one end of the armature 3, the latter being provided with aninsulating bushing 3 mounted upon an extension or stem 3 which engagesthe group. A spring-latch 9 engages and holds the switch-springdepressed, and this latch is provided at its upper end with an inclinedcam extension 9 which is engaged by the extension 3 in the upwardmovement of that end of the armature to trip off the latch and releasethe switch-spring.

The telephone set proper comprises a polarized ringer 10, receiver 11,transmitter 12, induction coil 13, battery ll, switch-hook 15, condenser16, and certain contact springs, described in connection with thecircuits.

The spools of the ringer 10 are wound in the usual manner, the windingsthereof being directly included in the drop wires R, L, which drop wiresform with the windings of the ringer an unbroken loop through thetelephone set.

17, 18, 15) and 20 designate a group of contact springs controlled andoperated by the armature 21 of the ringe The switch spring 17 of thisgroup is normally held in contact with the bottom spring 18 by aspringdatch which is provided at its upper end with a cam extension 22adapted to be engaged by a contact extension 21 carried by the armature,upon the upward movement of the latter, whereupon the switch-spring 17,which has a normal upward tension, is released, and rises so as to closecontact between'l? and 19 and 19 and 20. The return of the switch-springto normal latched engagement with latch 22 is etl'ected by the downwardmovement of the same end of the armature which effects the release onits upward movement.

The receiver 11 is included in a loop conductor 29 which connects thesprings 17 and 18 and is therefore normally short circuited. A conductor2 t connected with the right drop wire extends thence through condenser16, secondary winding of the induction coil 13, to and through thereceiver. and by conductor 23 to switch-spring 18. The transmitter,primary and local battery are included in a conductor 25 extending fromthe left drop wire to a top spring 26 which cooperates with theswitch-hook. A conductor 2? connecting the SWltClbllOOk with spring 19forms another part of the primary circuit, and a conductor '28connecting spring 20 with the left drop wire completes the primarycircuit. A bottom spring 29 contacts with the switch-hook when thelatter is depressed, and this spring is connected as indicated byconductor 31.

The pole relays, the telephone sets proper and the circuits are, orshould ordinarily be, exactly identical at each sub-station, with theexception that electrically-beyond the last )OlG relay a grounderinstrument is provider, which will. now be described: In so far asmechanical construction is concerned, this grounder K is or may beidentical with. one of the .pole relays, as J or J. The windings of thespools, however, are both alike and wound in the same direction. Theright-hand main line extends to and includes the winding of spool 32 andthence extends to and is connected with the lower contact spring 33.Similarly the left-hand main wire includes the windings of the spool 34and extends thence to and is connected with the switch-spring 35. Thetop spring 36 is connected to ground as indicated at 37. The normalposition of the grounder is with the switch-spring held down by thelatch-spring 38 in contact with bottom spring 33, thus closing thecircuit between the right and left main lines through the windings ofthe magnet.

There is shown associatedwith the pole relay J an emergency relay M.This instrument is not essential to the working of the system, and isomitted at the sub-station of which the pole relay J forms a part. De--scribing this relay, it comprises an ordinary, non-polarized magnetspool 39 wound extremely high and having its windings in cluded in ashunt wire 40, 40, which extends from the right main line on one side ofthe pole relay to the right main line on the other side thereof. MagnetM has an armature 41 normally held retracted by a spring 42 havingconsiderable tension, and in its retracted position this armature holdsback a contact spring 43 which is adapted when released to engage acoiiperating spring 44. These two springs are connected with the shuntwire 40, 40, respectively, in such manner as to cut out or short circuitthe windings of the instrument when the magnet is energized and spring43 released to close with spring 44. The end of spring 43 is hook-shapedso as to hook over the end of the armature 41 and hold the latter inclosed position when it has been once energized. The instrument must berestored manually and its function is to completely cut out the polerelay with which it is associated, when an emergency demands, 2'. 6.when the polerelay fails to operate properly.

The system is operated by sending pulsating current of one polarity forbuilding up the line, pulsating current of opposite polarity foroperating the ringer of the station selected, and ground to groundcurrent for restoring, for automatically arresting the building up ofthe sectional line, and for signaling purposes. I

Describing now the central station equipment, the two main line wiresterminate in an ordinary spring-j ack N, the tip-spring of whichnormally engages a contact'45 with which is connected a conductor 46which insprings are interconnected by conductors, as

54, 54, 55, 55, 56, 56, 57, 57 and 58, 58 in such manner that whenevereither key is moved in either direction it opens the series connectionsat each side which extend through the three keys, but normally the twoline wire circuits are extended uninterruptedly through the series ofkeys.

The central key B is the key which is operated in building up the lineand either 10- cating a party calling in for connection or selecting andringing the bell of a subscriber called for. Shifting this key in onedirection throws current on one end of the cord, and in the oppositedirection sends current over the opposite end of the cord. To giveconnection to a party calling in, the substation is so organized thatupon'removing the switch-hook a fiasl1ground is established from thesubstation in question through the grounded drop G of the correspondingjack; the bottom spring 29 of the switch-hook be ing to this endarranged to follow the switchhook until it engages top spring 26 and fora short period thereafter during the upward movement of the switch-hook.Upon observing the shutter of the drop fall, the operator plugs in andmoves the running-selecting key B, thus establishing circuit connectionswith the pole changer F as follows: from the tip of the plug toswitch-spring 50, through the two cooperating outer springs to conductor60, to conductor 60 and to the plus-or-minus binding post 60 of the polechanger, thence by conductor 60 to the plus contact 61 on one side ofthe pole changer I arm, through the corresponding spring 62 of the polechanger (when closed on that side) to the positive side of the battery63, from the opposite side of the battery to the other spring 64 on thesame side of the pole changer arm, thence to contact 65 and from thereby conductor 66 to the front spring 67 of a relay D, which spring isnormally closed with a switch-spring 68 of the relay. From the latterspring a conductor 69 leads back to the conductor 69 of the key, andwhich is connected with the outer spring of the group operated by theswitch-spring 50.

through the latter to ground at 76.

Switchspring 50 is connected with the sleeve of the corresponding end ofthe cord. Each movement of the pole changer arm which closes thiscircuit will, therefore, send an impulse of one polarity over theexternal or line circuit as long as the running-selecting key is heldover.

Assuming that the second station is the one from which the subscriberhas called in, the first impulse going over the external circuitdescribed will flow through the selecting relay J in the direction todraw down the left hand end of its armature, thus placing the switchspring 2 into latched engagement with latch 9. A space bushing interposed between the members t and 7 of this group of springs will preventspring 2 from contacting with spring 7 during this movement. Upon thedying away of the impulse, however, armature 3 will return to its normalposition, relieving the pressure from spring st and the space bushingcontrolled by the latter, whereupon spring 7 will rise into contact withswitch spring This peculiar operation of the spring group ef fects thebuilding up of the right hand sectional line without permitting any partof the building up impulse to flow on to the succeeding station. Thesame impulse which operates relay J will also flow through the ringer 10at that station, but inasmuch as its switch spring is normally inlatched position anu its armature moves in the latchingup direction,such movement will be ineffective. The clapper of the ringer will notstrike a blow when its armature is moved in this direction because ofthe peculiar connection of the clapper-stem with the armature, as willhereinafter appear.

The next impulse sent to line repeat at the second station the samemovements just described as having occurred at the first station.However, the subscriber by removing his receiver, and permitting theswitch-hook to rise, has partially established a grounding connectionwhich comes into operation and is effective as follows: as the left endof the armature 21 of the ringer at station I starts to close itencounters spring 19 and thus establishes a ground connection will tendto from the grounded armature through spring i 19, conductor 27,switch-hook and top spring 26, and that part of the primary circuitconnected with the drop line L, thence through the ringer and relay atthat station to the right main line, and over the latter to theright-hand side of key B. From switch spring 50 of this key the circuitis through a cooperating outer spring to conductor and thence by aconductor 71 to an auxiliary battery 72, and to and through the windingsof the relay D, thence by conductor 73 to one of the switch springs 74cof said relay, normally closed with a bottom spring 75, and

The escircuit connections of the line wires with the main battery,which, of course, arrests the further movement in one direction of thearmature of the ringer at station I and of the armature of the relay J.In this con nection it should be noted that the armatures 21 of theringers are unrest-rained in their initial movements and therefore moveduring the earliest part of the impulse, whereas the armatures of therelays J, J, etc., have comparatively heavy loads to overcome in theresistance of their respective spring groups before the latching-upmovement is effected, and it follows that the reversing re lay D hasample time to effect the reversal of the circuit before the particularpole relay concerned, as J, can operate.

The reversal of circuits referred to, as accomplished by relay D, iseffected by changing the connection of conductor 69 from contact 65 ofthe pole changer over to a contact 77 thereof on the opposite side, thisbeing done by the movement of switch spring 68 of relay D away fromspring 67 and into contact with top spring (37. From 67 a conductor 78leads to a spring 7 9 of the impulse counter, which normally engages acooperating switch spring 80, and from the latter a conductor 81 leadsto the said contact 77. lVith this contact a spring 64 of the polechanger cooperates, and the latter spring is connected by conductor 64with the positive side of the battery 63. Inasmuch as the left side ofthe main line is connected through key B with the plus-or-minus contact60 of the pole changer, no change in this connection is necessary toeffect the reversal being described.

The result of the operation of relay D is to arrest the building-up ofthe line at that station which has signaled in, and by changing thepolarity of the circuit through the ringer. cause the latter to ring.The ringer will, of course, continue to operate as long as the key B isheld over.

The first ringing stroke of the ringer at station 1 places the localcircuit in talking condition as follows: upon the rip-movement of member21 of the armature, the latch 22 is tripped off, whereupon switch spring17 separates from short-circuiting spring 18 and closes with springs 19and 20. This es tablishes the talking circuit,the primary from the leftdrop wire through the transmitter, primary, battery, spring 26 andswitch-hook, to springs 19 and 20, and thence by conductor 28 back tothe left drop wire, and the secondary circuit, from the left drop wirethrough 28 to springs 20, 19 and 17, from the latter over conductor 17to the receiver, and from the other side of the latter back throughcondenser 16, secondary winding of the induction coil and conductor 24to the rightdrop wire.

It should be noted that relay D when it operates closes a holdingcircuit through itself which remains unbroken .until key B is returnedto normal. This circuit is from battery 72, over 71 to outer springs ofkey B, back over conductors 69 and 82 to springs 83 and 84L of therelay, (now closed) and by 85, 73 and 71, to and through the windings ofthe relay and to battery.

The operation of selecting a called-for party is efiiected by plugginginto the jack of the party wanted and using the same key B described,but this operation involves also the use of the impulse counter E. Thisinstrument comprises an escapement wheel 86 and circular cam E mountedfixedly upon a main shaft 87 which is spring returned; the escapementwheel being controlled by an armature 88 actuated by a magnet E forminga part of this instrument. The impulse counter is set by grasping athumb-nut (not shown) mounted upon the end of the main shaft androtating the escapement wheel against the action of its spring as manysteps or ratchet notches as the number of impulses to be counted out.The circular cam cooperates with and controls two groups of contactsprings through the medium of cam projections 89 and 90 respectivelymounted on springs 91 and 92. In the normal position, these wipers 89and 90 engage diametrically opposed notches in the periphery of the cam,but whenever the cam is rotated out of its normal position the wipersride out of the notches and upon the periphery of the cam, and in sodoing change the circuits through the'groups of contact springscontrolled thereby, as will appear in connection with the tracing of thecircuits. It may be noted at this point that when the impulse counterreaches its zero position the circuits are automatically restored tonormalby the movement of the wipers 89 and 90 into the notches of thecam E.

The mechanism is so organized that after the impulse counter has beenset for a redetermined count, and the key B held over, impulses from oneside of the pole changer pass to line or over an external circuit, andimpulses from the opposite side of the pole changer pass through themagnet E of the impulse counter and actuate the escapement. It isessential that no fragmentary impulse should be sent over the externalcircuit as otherwise certainty of selection would be from contact 95slightly and arrested by stop 94. The'first impulse after the key B hasbeen closed, if it happens to be from that side of the pole changerwhich is connected with the external circuit, would be inefiectivebecause of the interruption of the circuit between arm 93 and stop 95.The next impulse of opposite polarity would pass over the local circuitand operate the escapement, thereby closing the external circuit, andthereafter the impulses would go alternately over the external and localcircuits.

The operation of building up the line from station to station whileselecting a called party is precisely the same as in the case ofanswering a calling party, until the requisite number of impulses havebeen counted out by the impulse counter, and thereupon the arrival ofthe latter at normal automatically reverses the circuits and rings thebell of the selected station.

Before tracing the circuits through the im pulse counter it may be notedthat as soon as the latter instrument is moved from normal in settingit, it closes a circuit through the reversing relay D so that the latteris held in what may be termed its reversed position during'the entireact of selecting a called-for party. This holding circuit is frombattery 72 over conductors 71 and 96 to spring 92 of the impulsecounter, from the latter to contact spring 97,- and thence by conductor98 to conductors 7 3 and 71 which extend through the windings of therelay "D and back to the opposite side of the battery.

The local circuit established through the impulse counter by closing keyB is from the intermediate one of the two outer springs engaged byswitch spring 50 over conductors 99 and 100, to and through magnet E, totop spring 101, at this time closed with switch spring 80. From thelatter over conductor 81, contact 77 pole changer spring 64, conductor6s, to the positive slde of battery 63. From the opposite side of thebattery'by conductor 63, to pole changer spring 62, contact 102,conductor 103, to plus-or-minus terminal and thence over conductors 60and 60 back to the outer spring of the pair operated by switch spring50.

The exchange end of the external circuit may be traced from the outerspring of the pair actuated by switch spring 50, over conductors 69 and69, to switch spring 68 of re lay D now closed with top spring 67, fromthe latter over conductor 78, to spring 7 9 of the impulse counter, nowclosed with spring 91, from the latter over conductor 104, to arm 93 nowclosed with contact 95, from the latter over conductor 105, to contactof the ioo pole changer, thence through spring 64 and conductor 63 tothe main battery, and from the opposite side of the latter over 6%, tospring 62, contact 61 and conductor 60, to the plus-or-minus contact60". From the latter the circuit is over conductors 60 and 60, to theleft side of the master-key, and so out to the lefthand main line. Theexternal circuit is, of course, out over one main line and back over theother.

The automatic reversal at the end of the predetermined count which ringsthe bell of the subscriber called, is accomplished by the return of theimpulse counter to normal thereby changing that part of the externalcircuit which theretofore extended through conductor 78 and springs 79and 91, to springs 79 and 80, and conductor 81 to con tact 77 at theopposite side of the pole changer: the circuit from 7 7 through thebattery and back to contact 102 of the pole changer and theplus-or-minus contact 60 complete that part of the circuit which isreversed.

After a party has been given talking connections, has finished hisconversation, and hangs up his receiver, the clearing-out signal H atCentral is operated. By depressing his switch-hook, when any party hastalking connection.- he establishes a ground circuit from 30 to thebottom spring 29 of his switch-hook, thence through the switch-hook,conductor 27, springs 19 and 20, and conductor 28 to the left main line.From the left main line the circuit at Central is from the inner spring,now in contact with switch spring 50 of key B, over conductor 56 to abranch conductor 106, which extends through lamp relay H, and battery107 to ground. The closing of re lay H closes a local lamp circuit andilluminates the supervisory or clearing lamp 108; The restoring of thelines which have been in use is now in order, and is accomplished asfollows: the restoration of any line with which the cord circuit isconnected is accomplished by sending a grounded circuit from ground atCentral over the left main line to a ground established at the extremeend of this line, and before this latter ground can be established it isnecessary to build up the sectional line to reach the grounder K which,as hereinbefore described, is similar to one of the relays J or J and isoperated by precisely the same kind of a selecting impulse. The impulsewhich reaches and operates this instrument K moves the latch-engagingend of its armature upwardly, thereby tripping off the latch andpermitting switch spring 35 to close with grounding spring 36. Thisplaces the line in condition for restoring. To restore, the operatormoves key A or C, as the case may be, in a direction away from key B.This closes the circuit from the tip side of the cord through switchspring 48, outer spring engaging the latter, conductor 109, withnegative side of main battery 63, from the other side of the batteryback over the conductor 110 to the two outer springs actuated by spring*8, that one next to spring 48 being insulated therefrom. From theinsulated spring a conductor 111 leads to ground. The placing of theleft line direct to ground through the main battery secures an impulseof any desired duration, so that the several relays in series in thiscircuit are operated with certainty. Those spools which act as restoringmagnets and which are included in this restoring circuitare the spools 1of the several selecting relays J, J, etc, and the spool 34 of thegrounder. The latter spool, it will be noted, is energized in suchmanner as to restore the grounder to its normal, 2'. c. latchedcondition. The master-key consisting of the three keys A, B and C, issymmetrical in so far as its connections are concerned, and accordinglythe operations on either end of the key are alike both as to locatingand selecting the calling-in subscriber, selecting a called subscriber,and restoring.

It has been stated that before restoring it is necessary to build up theline to the grounder K. Inasmuch as it would be an unfair distributionof service, particularly in the case of party-lines having a largenumber of sub-stations, to restore the whole line and commence at thestation nearest Central always after each conversation, means areprovided whereby the exchange operator, upon receiving the signal torestore, may locally restore the single subscriber who was given talkingconnections, then proceed farther along the line and pick up and givetalking connections to the next subscriber in order, who may have sethis stat-ion for a connection by removing his receiver, as hereinbeforedescribed. Local restoring is accomplished by sending a single metalliccircuit impulse through the ringer of the subscriber who has been rungon and in the proper direction to restore that instrument, viz: in adirection opposite that of the ringing current. This local clearing isaccomplished by closing either key A or C in a direction toward B, and,as will be seen by the circuits now to be traced, this closes the mainbattery direct to the external line without. )HSSlD throu 'h the )ole Ichanger and without establishing grounds. Assuming key A has beenoperated for local clearing, the circuit from the tip side of the lineis from switch spring 49 and cooperating outer spring over a conductor112 to 110 and the positive side of the battery, and from the oppositeside back over conductors 109 and 113 to the outer spring whichcooperates with switch spring 49; the latter being, of course, connectedto the sleeve side of the main line. The closing of this circuit movesthe armature of the ringer in the direction to latch the switch spring17, and, by closing with bottom spring 18, short circuits the receiver,thereby disabling the talking circuit.

It is often necessary to place two parties on the same line in talkingconnection with each other. This is accomplished as follows: the partywho calls in is located and rung on as usual, whereupon he gives hisorder for the party wanted. If the party wanted be between his stationand Central the operator asks him to hang up his receiver for a moment,thus establishing a ground at his station, whereupon she operates therestoring key, and, of course, restores the line, without, however,disabling his talking connections because the restoring circuit flows toground at 30 without passing through the windings of his ringer.Thereupon she simply sets the impulse counter for the number of theintermediate station desired and calls that subscriber. The two then arein talking connection; the condensers 9 being in series with andbridging (for talking purposes) the interrupted right-hand line betweenthe station nearest Central and the other station.

In case the party to be called should be located farther from Centralthan the party calling, the operation of putting the two together wouldbe changed to the extent of first locally restoring the callingsubscribers station, then, wlth the impulse counter selecting thefarther subscriber, immediately restoring without local clearing andthen calling the original subscriber with the impulse counter. r

The function of the emergency relay M, shown as located at station hasbeen hereinbefore referred to. It is a feature of the present systemthat failure of any part of the subscribers set proper to operateproperly does not interfere with the proper operation of the select-ingrelay controlling that station, so that the sub-stationsare not in anysense interdependent so long as the se locting relays operate properly.Failure of a selecting relay may be due either to a bad contact betweenits normally closed springs 2 and 4, or to an interruption of the bridging loop formed by the drop'wires. Either of these conditions wouldprevent the magnet of the selecting relay operating. Inasmuch, however,as the left line extends uninterruptedly to and through the nextselecting relay, at which instrument the bridging connection to theright line will be intact, it follows that sufficient current can beforced through the emergency relay M. which is bridged across theinterruption of the right main line, by simply putting on enough voltageat the exchange to operatesaid emergency relay notwithstanding the factthat it is extremely high wound and heavily tensioned. To this end,there provided at Central anauxiliary battery 114, and auxiliary'key 115whereby the auxiliary battery may be added to the main battery 63. Theconnections are, as clearly shown in the diagram, such that by simplypressing the switch spring 116 of the key into contact with the bottomspring 117 the two batteries are placed in series. The voltage ofbattery 11 1 will be such that added to that of the main battery it willoperate the emergency relay M, and inasmuch as the closing of the lattercauses it toremain permanently closed, and thus cuts out the particularsub-station to which it pertains, it will be obvious that any disabledstation may be readily cut out, and the line thus made available for therest of the subscribers.

The exchange operators listening set is shown at O and is arranged in ausual manner; the listening key of the set being designated 11S.

Describing now the principal selecting instruments employed at thesubstation, viz: the selecting or pole relay and the combined ringer andrelay, and referring first to Figs. 3, and 7 wherein the pole relay isshown, 1 and 1 designate the spools, 3 the armature, 2, 4 and 7 theseveral springs of the contact group, 9 the latch, 9 the cam portion ofthe latch, 8 the member which cooperates with the cam, and 3 aninsulating bushing which engages and actuates the group of springs. Thearmature is pivoted, as usual, between a pair of upstanding ears formingpart of a yoke plate designated as a whole 120. The yoke has ahorizontal extension at its right-hand end 121 to which the group ofsprings is attached, and at its opposite end a down-turned extension 122to which the latch is attached. The biasing bar 123v is connected atitslower end to a heel-piece 12st (Fig. 5) and at its opposite endoverhangs the central portion of the armature in the usual manner.

An insulating bushing 125 is seated immovably in contact spring 7,extends freely through an opening in spring 2 and engages the under sideof spring 4, as shown clearly in Fig. 7. It follows that during thedepression of spring 4:, that spring and the switch spring 2 remain incontact until the latter has been engaged with the latch and thepressure upon spring 4: relieved, whereupon the tension of spring 7causes it to rise into contact with the switch spring; the bushinglifting spring 4 out of contact.

Below the overhanging lip or notch memher 126 of the latch member 9 at adistance slightly in excess of the thickness of the switch spring isthrown out an integral step 127; this stop member standing outwardlysufficiently beyond the member 126 to positively arrest the downwardmovement of the latch spring under the action of the armature. Thefunction of this stop is to prevent sparking between the switch spring 2and overlying spring 4, which would otherwise occur at the end of thedown-stroke of the armature.

Describing the ringer, this instrument is in general like the polerelay, and most of the parts thereof have been described in con nectionwith the description of circuits therethrough; corresponding parts beingsimilarly designated by the reference numerals. Describingthe contactgroup, however, somewhat more specifically, the numbers thereof areshown in normal position in Fig. 8, wherein it will be seen that thearrangement is somewhat different from that shown diagrammatically butnevertheless corresponding springs are correspondingly designated. Thatis to say, springs 17 and 18 are normally closed with each other andshort-circuit the receiver, a pair of grounding springs are shown inthis group to avoid using frame as any part of the circuit, andaccordingly switch spring 19 serves as one of the grounding springs, anda bottom spring 21 corresponds to the part similarly designated in thediagram. This bottom spring is provided with an extension 21 which isbent outwardly around the edge of the spring 19 and returns so as tooverhang the latter; the return portion carrying the contact point andforming that part with which the bushing of the armature engages indepressing the group. An insulating bushing 128 rests atits lower endupon the yoke frame 129 of the ringer and extends upwardly through allof the members of the spring group, except the uppermost. Spring 18rests upon a ledge or annular shoulder upon the bushing and is to allintents immovable. Accordingly when spring 19 is unlatched it rises, andin so doing a stud 130 carried thereby encounters spring 17 and forcesit upwardly into contact with top spring 520, at the same time openingthe contact between 17 and 18. Bottom spring 21 has an upwardlyfollowing tension which keeps the grounding contacts separated at alltimes, except during the time the pres sure of the armature is upon thegroup. In short, in the normal position, contact is closed between 17and 18 only, and in the talking circuit position contact is closedbetween springs 19, 17 and 20 only.

The clapper stem 131 of the armature is rigidly connected with a pivotbracket 132 (shown in plan view in Fig. 6), which pivot bracket isprovided with a laterally extending arm 133 (see Fig. t) which restsclose to the under side of the armature. The pivot bracket is pivotallyconnected to the armature by two studs 13 1 and 135 which extend intosuitable apertures in the armature; a pivot pin 136 being extendedthrough the armature and these studs. In practice an extension of theclapper stem forms the stud 13 1. This connection pivots the clap per tothe armature in such manner that the. armature is free to move in onedirection. viz: in the direction to depress its spring group, withoutmoving the clapper, but upon movement in the opposite direction thearmature engages the arm 133 and 0scillates the clapper positively. Acoiled contractile spring 137 normally holds the loosely pivoted clapperagainst a stop stud 138. The operation of these parts has been fully setforth in connection with the description of the diagram.

\V iile we have herein shown a preferred embodiment of the severalfeatures of the invention, yet the invention is not to be understood aslimited, in its broader aspect, to details of either construction orarrangement.

e claim as our invention:

1. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said sub-stations, means practically sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach sub-station, a bridging loop conductor normally connecting saidmain wires at each sub-station, a selecting relay at the juncture of themain wires and loop, and a subscribers telephone set associated withsaid loop and connected to the main wires solely through the two limbsof said loop.

2. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said substations, means practically sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach. sub-station, a bridging loop conductor normally connecting saidmain linewires at each substation, a selecting relay at the juncture ofthe main wires and loop and included in said bridging loop conductor,contact devices o-perated by said selecting relay for building up saidsectionalized line wire, as regards direct current of normal operatingpotential, and a subscribers telephone set associated with said loop andconnected to the main wires solely through the two limbs of said loop.

3. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said sub-stations, means practically sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach sub-station, a bridging loop conductor normally connecting saidmain wires at each sub-station, a

selecting relay at the juncture of the main wires and loop, and having awinding included in series in said loop, switching contact devicesoperable by said relay for disabling the direct current circuit throughsaid loop and establishing a direct current circuit from one section ofthe sectionalized line to the next, a condenser bridge across thewinding of said relay included in said bridging loop, and a subscriberstelephone set associated with said loop.

4. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said sub-stations, means practically.sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach sub-station, a bridging loop conductor normally connecting saidmain wires at each sub-station, a selecting relay at the juncture ofsaid main wires and loop, and having a winding included in series insaid loop, switching con tact devices operable by said relay fordisabling the direct current circuit through said loop and establishinga direct current circuit from one section of the sectionalized line tothe next, a condenser bridge across the winding of said relay includedin said bridging loop, and a subscribers telephone set associated withsaid loop, and means, operable from a central station, for restoring theseveral selecting relays to normal.

5. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said sub-stations, means practically sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach sub-station, a bridging loop conductor normally connecting saidmain wires at each sub-station, a selecting relay at the uncture of themain wires with said bridging loop, having two magnet windings, one ofwhich is included inone of said main line wires and the other includedin said bridging loop conductor, contacts operable by said selectingrelay for building up said sectionalized main line wire, as regardsdirect current of normal operating potential, a subscribers telephoneset associated with said bridging loop, and means for establishing arestoring ground to ground circuit from a central station through thewindings of the several relays included in said main line to ground at apoint beyond said relays.

6. In combination, an uninterrupted main line wire extending through aplurality of sub-stations, a companion main line wire likewise extendingthrough said sub-stations, means practically sectionalizing one of saidline wires, as regards direct current of normal operating potential, ateach sub-station, a bridging loop conductor normally connecting saidmain wires at each substation, a selecting relay at the juncture of themain wires with said loop, said relay comprisin two windings on onemagnet core, both o which are included in the main line wires, and athird winding upon a second core, included in said bridging loop, anarmature forming a member of said relay, movable in one direction whencurrent is sent through the bridging loop winding and movable in anopposite direction when current is sent through one of the windingsincluded in a main line, contacts operable by said relay for effectingthe building up of said sectionalized main line as regards directcurrent, a subscribers telephone set associated with said bridging loop,and means for establishing a restoring circuit from ground at a centralstation through the several operated selecting relays to ground at astation beyond.

7. In combination, an uninterrupted main line wire extending througha,plurality of sub-stations, a companion main line wire likewiseextending through said sub-stations, means practically sectionalizingone of said line wires, as regards direct current of normal operatingpotential, at each substation, a bridging loop conductor normallyconnecting said main wires at each sub-station, a polarized selectingrelay at the juncture of the main wires and loop, switching contactsoperable by said relay to build up the sectionalized line wire, asregards direct current when said relay is actuated by current of onepolarity, means actuated by said relay for restoring said switchingcontacts when operated by current of opposite polarity, and asubscribers telephone set controlled by said selecting relay.

8. In a party-line telephone apparatus, anuninterrupted main line wireextending through a plurality of sub-stations, a companion main linewire likewise extending through said sub-stations, means practicallysectionalizing one of said line wires, as regards direct current ofnormal operating potential, at each sub-station, a drop wire connectedwith one of said main wires at each sub-station, a subscribers telephoneset associated with said drop wire, and a selecting relay at thejuncture of the main wire with said drop wire, said relay comprising apolarized magnet and its armature, a switch spring, one or morecooperating contacts, a latch arranged to cooperate with said switchspring, and operative connections between the armature and said latch,whereby movement of the armature in one direction moves the switchspring into latched engagement and movement of the armature in theopposite direction trips of the latch.

9. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at ditferentsub-stations, a pair of line wires extending from Central through theseveral sub-stations and means for successively and progressivelyestablishing link circuits from the central station through thesuccessive substations, of means for automatically arresting theprogressive establishment of said link circuits comprising manuallyoperable means at each of the sub-stations for partially establishing aground connection, electricallyactuated means, operable from the centralstation, for completing said ground connection at the sub-station, andautomatic means operable by the establishment of said ground circuit forarresting the progressive closing of said link circuits.

10. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at differentsub-stations, a pair of line wires extending from Central through theseveral sub-stations and means for successively and progressivelyeffecting a selection by establishing return circuits from the centralstation through the successive sub-stations, of means for automaticallyarresting the progressive establishment of said return circuits,comprising manually operable means for partially establishing analternative return circuit from each sub-station, electricallyactuatedmeans for completing said alternative return circuit, and automaticmeans brought into operation by the establishment of said alternativereturn circuit for arresting the progressive selection of stations.

11. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at differentsub-stations, a pair of line wires extending from Central through theseveral sub-stations and means for successively and progressivelyeffecting a selection by establishing return circuits from the centralstation through the successive sub-stations, of means for automaticallyarresting the progressive establishmentof said return circuits,comprising manually operable means for partially establishing analternative return circuitfrom each sub-station, electricallyactuatedmeans for completing said alterna tive return circuit, and automaticmeans brought into operation by the establishment of said alternativereturn circuitfor arresting the progressive selection of stations, saidmeans comprising a relay at the central station included in saidalternative circuit and switching contacts controlled by said relaywhich in turn control the source of operating current.

12. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged atditferentsub-stations, a pair of line wires extending from Central through theseveral sub-stations and means for successively and progressivelyeffecting a selection by cstablishing return circuits from the centralstation through the successive sub-stations, of means for automaticallyarresting the progressive establishment of said return circuits,comprising manually operable means for partially establishing analternative return circuit from each sub-station,electrically-actuatt-id means for completing said alternative returncircuit, and automatic means brought into operation by the establishmentof said alternative return circuit for arresting the progressiveselection of stations, said means comprising a relay at the centralstation included in said alternative circuit and switching contactsoperable by said relay and operating to reverse the polarity of theoperating current flowing to line.

13, In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at differentsub-stations, a pair of line wires extending from Central through theseveral sub-stations, one of said line wires being sectionalized asregards direct current of normal operating potential, and means forsuccessively and progressively establishing link circuits from thecentral station through the successive sub-stations comprising aselecting relay associated with each sub-station for building up saidsectional line, a second relay associated with each sub-station forarresting operation of the corresponding selecting relay, manuallyoperable means for partially establishing an alternative return circuitfrom each sub-station, cooperative means operated by said second relayfor completing the establishment of said alternative return circuit, arelay at the central station, and means operable by said latter relayand operating to deprive the selecting relay of building-up current.

14-. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at differentsub-stations, a pair of line wires extending from Central through theseve 'al sub-stations, one of said line wires being sectionalized asregards direct current of normal operating potential, and means forsuccessively and progressively establishing link circuits from thecentral station through the. successive sub-stations comprising aselecting relay associated with each sub-station for building up saidsectional line, a second relay associated with each sub-station forarresting operation of. the corresponding selecting relay, manuallyoperable means for partially establishing a grounded return circuit fromeach sub-station, cooperative means operated by said second relay forcompleting the establishment of said grounded return circuit, a

relay at the central station, and means operable by said latter relayand operating to deprive the selecting relay of building-up current.

15. In a party-line telephone system, the combination with a centralstation, a plurality of subscribers telephone sets arranged at differentsub-stations, a pair of line wires extending from Central through theseveral sub-stations, one of said line Wires being sectionalized asregards direct current of normal operating potential, and means forsuccessively and progressively establishing link circuits from thecentral station through the successive sub-stations comprising aselecting relay associated with each sub-station for building up saidsectional line, a second relay associated with each sub-station forarresting operation of the corresponding selecting relay, manuallyoperable means for partially establishing an alternative return circuitfrom each substation, cooperative means operated by said second relayfor completing the establishment of said alternative return circuit, arelay at the central station, and means operable by said latter relayand operating to deprive the selecting relay of building-up current, aringer relay associated with each sub-station for arresting operation ofthe corresponding selecting relay, said ringer relay comprising apolarized magnet and its armature, a clapper operatively connected tomove positively with the armature in one direction and to remaininactive during movement of the armature in the opposite direction, anda group of switching contacts operable by said armature, manuallyoperable means for partially establishing a grounded return circuit fromeach sub-station, circuit connections through the group of contactscontrolled by said ringer for completing the establishment of saidgrounded return circuit a relay at the central station included in saidgrounded circuit, and means operable by said latter relay for reversingthe polarity of the operating current flowing to line whereby theselecting relay is prevented from performing its building-up functionand the ringer relay is operated in the ringing direction.

16. In a party-line telephone system, a central station and a pluralityof sub-stations, a line wire extending through said sub-stations, aplurality of condensers connected in series in said wire, onecorresponding to each sub-station except the last, direct current returncircuit connections from each sub-station to the central station, anelectromagnetic selecting mechanism at each substation interposed insaid line wire and con trollable through the several return circuitconnections.

17. In a party-line telephone system, a line wire extending through aplurality of substations, corresponding condensers associated with saidline wire at each sub-station and normally interposed in series in saidline wire and electromagnetic station selecting mechanism arranged inshunt relation to the condensers at each sub-station.

18. In a telephone system, a normally continuous line wire and acompanion sectionalized line wire comprising sections extending from thecentral station to the first sub-station, and from sub-station tosub-station beyond, means acting to balance said lines electricallyunder induction due to high frequency current comprising a condenserinterposed and normally connected in series between the contiguous endsof each of the several sections of said sectionalized wire and selectivemechanism interposed in said sect-ionalized wire.

19. In a party-line telephone system, a line wire extending through aplurality of substations, condensers interposed in series'in said linewire whereby it is sectionalized, as regards direct current, lock-outmechanism controlling the talking circuit at each substation, mechanismfor building up said line wire around the condensers, and mechanism forrestoring the apparatus to normal.

- 20. In a party-line telephone system, a pair of line wires extendingthrough a plurality of substations, condensers interposed in series inone of said line wires, whereby it is sectionalized as regards directcurrent, and relay mechanism at each sub-station interposed in the samewire with the condensers. I

21. In a party-line telephone system, a pair of line wires extendingthrough a plurality of sub-stations, condensers interposed in seriesin'one of said line wires, whereby it is sectionalized as regards directcurrent, mechanism for building up said sectionalized line wire pasteach condenser, lock-out mechanism at each sub-station, and means forrestoring parts of the sectionalized line wire to normal independentlyof the restoration of said lock-out mechanism.

22. In a party-line telephone system, a pair of line wires extendingfrom a central station through a plurality of sub-stations, condensersinterposed in series in one of said line wires, whereby it issectionalized as regards direct current, a relay associated with eachcondenser operable to build up said sectionalized line wire past thecondenser, lockout mechanism at each sub-station operable independentlyof said building-up relays, and means operable from the central stationfor restoring the sectionalized line from Central through any desirednumber of sub-stations.

23. In a party-line telephone system, a pair of line wires extendingthrough a plurality of sub-stations, condensers normally interposed inseries in one line, whereby it is sectionalized as regards directcurrent at each sub-station, lock-out mechanism at each sub-station, andmeans for establishing a full metallic uninterrupted talking circuitfrom Central through one sub-station and a talking circuit through oneor more of the said line condensers as to another more remote station.

24. In a party-line telephone system, a pair of line wires extendingfrom a central station through a plurality of substations, one of saidline wires being sectionalized as regards direct current, a selectingrelay corresponding to each sub-station and operable to build up thesectional line past said station, a subscriber's telephone set andassociated lock-out mechanism at each sub-station, said lock-outmechanism being operable independently of the corresponding selectingrelay, and mechanism organized to restore a given lock-out mechanismindependently of or without restoring lock-out relays, whereby theprogressive building up of the line may be continued from anyintermediate station after the subscriber last connected in has beenlocked out.

In a party-line telephone system, a pair of line wires extending througha plurality of substations, one of said line wires being divided intosections corresponding to the sub-stations, as regards direct current,selecting relays corresponding to the several sub-stations and operableto build up said sectional line, and lock out mechanism at eachsub-station including a polarized relay operable independently of thecorresponding selecting relay, each selecting relay comprising twowindings arranged to inductively oppose each other when said relay isincluded in a metallic link circuit and said polarized relay beingarranged in a bridging loop extending across the two main lines, wherebythe latter relay may be operated independently of the selecting relays.

26. In a party-line telephone system, a pair of line wires extendingthrough a plurality of sub-stations, one of said line wires beingdivided and of sections corresponding to the several stations, aselecting relay corresponding to each sub-station, the magnet whereofcomprises two windings, one included in each of the main line wires, abridging loop and a lock-out mechanism at each sub-station, saidlock-out mechanism comprising a relay, .the windings whereof areincluded in the bridging loop, means for sending current over a metalliclink circuit including the two main line wires and bridging loop, andmeans tor establishing a circuit from ground at Central through one ofthe main lines to ground at a point beyond one or more of said selectingrelays, whereby the latter operate to restore the sec-- tionalized lineto normal.

27. In a party-line telephone system, the combination of a pair of linewires extending through a plurality of sub-stations, one of said linewires being normally separated into sections corresponding to thestations, a normally closed bridging loop at each sub station, aselecting relay at each sub-station operable to build up said sectionalline, and an emergency relay arranged in a high resistance shuntbridging the gap between the contiguous ends of the sectional line,inoperative under normal selecting current but responsive to current ofgreater power and operable to complete a circuit of lower re sistanceacross the same gap.

28. In a party-line telephone system, a main line comprising a pair ofline wires extending from Central through a plurality of sub-stations, abranch circuit wire leading from the main line at a sub-station,lock-out mechanism included in said branch circuit wire, and anemergency relay located at the juncture of the branch and main lines,inoperative under normal current and operable under abnormal current,and controlling switch contacts operable to throw said lockout mechanismout of operative connection with the main line.

29. In a party-line telephone system, the combination of a pair of linewires extending through a plurality of sub-stations, one of said linewires being normally separated into sections corresponding to thestations, a normally closed bridging loop at each substation, aselecting relay at each sub-station operable to build up said sectionalline, and an emergency relay arranged in a high resistance shuntbridging the gap between the contiguous ends of the sectional line,inoperative under normal selecting current but responsive to current ofgreater flow and operable to complete a circuit of lower resistanceacross the same gap, said relay comprising switching contacts and meansoperating to hold the switching contacts controlled thereby permanentlyclosed after operation.

30. In a party-line lock-out system, the combination with a subscriberstelephone set, of a stationselecting relay, an associated local circuitcontrolling relay, a local bat.- tery circuit, contacts operable by saidlatter relay for partially completing said local battery circuit, andother contacts, manually operable, for completing the establishment ofsaid local battery circuit.

31. In a party-line lock-out system, the combination with a subscriberstelephone set, of a station selecting relay, an associated local circuitcontrolling relay, a local battery transmitter circuit, an associatedreceiver circuit, contacts operable by said local-circuit controllingrelay for partially closing the local battery circuit and placing inoperative condition the receiver circuit,

and other, manually operable, contacts for closing the transmittercircuit, and switchcompleting said local battery transmitter hookcontacts operable to complete said local circuit. battery transmittercircuit when the switch- 32. In a party-line lggck-out system, the hookis released and rises. 5 combination With a su scribers te ephone set,of a station-selecting relay, an associated EV local-circuit-controllingrelay, a local bat} Witnesses:

EMILIE ROSE, FRANK L. BELKNAP.

tery transmitter circuit, an associated receiver clrcult, contactsoperable by sald lo- 10 cal-circult-controlling relay for partially

